爪哇从MIDI键盘获取输入

Question

我已经设计了我自己的合成器在java中，我现在想要连接它与MIDI键盘。我的课程通过所有有变送器的MIDI设备进行搜索。它成功找到我的midi键盘。我为每个设备添加自己的接收器到每个发射器，以便它可以接收所有可能的东西。从阅读所有的帮助文档和java文档，我知道发送器将MidiEvent发送给接收器，然后使用发送方法处理它们。所以我编写了自己的实现Receiver的内部类，并使用println语句来检查send方法中是否检测到任何东西。然而，没有任何东西被拿起。似乎没有什么帮助做这样一个简单的事情，我已经看过每个帮助文件，javadoc和论坛。我敢肯定，这肯定是一件非常明显的事情，我不知何故错过了。

我的合成器不应该与界面合成器混淆，它不是一个MIDI设备。它使用合成算法并具有播放方法。基本上我只需要让midi键盘发送关于将调用播放方法的事件的注释。

import javax.sound.midi.*; 
import java.util.ArrayList; 
import java.util.List; 
import java.io.*; 
public class MidiHandler 
{ 
    //ArrayList of MidiDevices 
    private ArrayList<MidiDevice> devices = new ArrayList<MidiDevice>(); 

    public MidiHandler() 
    { 
     MidiDevice device; 
     MidiDevice.Info[] infos = MidiSystem.getMidiDeviceInfo(); 
     for (int i = 0; i < infos.length; i++) { 
      try { 
       device = MidiSystem.getMidiDevice(infos[i]); 
       //does the device have any transmitters? 
       if (device.getTransmitters().size() > 0) { 
        //if it does, add it to the device list 
        System.out.println(infos[i] + ": " + device.getTransmitters().size()); 
        devices.add(device); 
       } 
      } catch (MidiUnavailableException e) {} 
     } 
     //if any transmitting devices were found 
     if(devices.size()>0) { 
      //for each device 
      for(int i = 0; i<devices.size(); i++) { 
       try { 
        //get all transmitters 
        List<Transmitter> transmitters = devices.get(i).getTransmitters(); 
        //and for each transmitter 
        for(int j = 0; j<transmitters.size();j++) { 
         //create a new receiver 
         transmitters.get(i).setReceiver(
          //using my own MidiInputReceiver 
          new MidiInputReceiver(devices.get(i).getDeviceInfo().toString()) 
         ); 
        } 
        //open each device 
        devices.get(i).open(); 
        //if code gets this far without throwing an exception 
        //print a success message 
        System.out.println(devices.get(i).getDeviceInfo()+" Was Opened"); 
       } catch (MidiUnavailableException e) {} 
      } 
     } 
    } 
    //tried to write my own class. I thought the send method handles an MidiEvents sent to it 
    public class MidiInputReceiver implements Receiver { 
     public String name; 
     public MidiInputReceiver(String name) { 
      this.name = name; 
     } 
     public void send(MidiMessage msg, long timeStamp) { 
      System.out.println("midi received"); 
     } 
     public void close() {} 
    } 
} 

注： 我已经看到了这一点：Java MIDI - getting data from piano?。

这：http://www.jsresources.org/examples/MidiInDump.html

接口音序看着方式复杂，我想也是。

Answer 1

我发现MidiDevice的getTransmitters（）似乎返回当前已经开发射器，而不是发射是可要打开的列表。我相信打开一个新的发射器的方式是通过getTransmitter（）方法。我已经修改了你的代码要做到这一点：

import javax.sound.midi.*; 
import java.util.ArrayList; 
import java.util.List; 
import java.io.*; 
    public class MidiHandler 
{ 

    public MidiHandler() 
    { 
     MidiDevice device; 
     MidiDevice.Info[] infos = MidiSystem.getMidiDeviceInfo(); 
     for (int i = 0; i < infos.length; i++) { 
      try { 
      device = MidiSystem.getMidiDevice(infos[i]); 
      //does the device have any transmitters? 
      //if it does, add it to the device list 
      System.out.println(infos[i]); 

      //get all transmitters 
      List<Transmitter> transmitters = device.getTransmitters(); 
      //and for each transmitter 

      for(int j = 0; j<transmitters.size();j++) { 
       //create a new receiver 
       transmitters.get(j).setReceiver(
         //using my own MidiInputReceiver 
         new MidiInputReceiver(device.getDeviceInfo().toString()) 
       ); 
      } 

      Transmitter trans = device.getTransmitter(); 
      trans.setReceiver(new MidiInputReceiver(device.getDeviceInfo().toString())); 

      //open each device 
      device.open(); 
      //if code gets this far without throwing an exception 
      //print a success message 
      System.out.println(device.getDeviceInfo()+" Was Opened"); 


     } catch (MidiUnavailableException e) {} 
    } 


} 
//tried to write my own class. I thought the send method handles an MidiEvents sent to it 
public class MidiInputReceiver implements Receiver { 
    public String name; 
    public MidiInputReceiver(String name) { 
     this.name = name; 
    } 
    public void send(MidiMessage msg, long timeStamp) { 
     System.out.println("midi received"); 
    } 
    public void close() {} 
    } 
} 

在我的硬件（我已经插入一个简单的USB MIDI控制器），代码正确地打印出“MIDI收到”创建MidiHandler的实例后。

希望这会有所帮助！

Answer 2

我发现你必须在调用setRecceiver（）之前打开设备，否则接收者的send（）方法会被上次运行应用程序时的任何垃圾MIDI数据调用。

device.open(); 

Transmitter trans = device.getTransmitter();  
// set new receiver after opening so that the input buffer will be flushed 
trans.setReceiver(new MidiInputReceiver(device.getDeviceInfo().toString()));